FC5 system crashes at random when using mouse

[Paul Johnson]

On a Dell Optiplex 270 running FC5, a very strange thing has started
to happen.  The machine runs fine and allows ssh logins and I've
worked on it for hours remotely.  It can remotely display jpeg files,
do anything I ask.

However, about once per day, the system crashes when people sit in
front of it and use the mouse & keyboard.  I've only seen the crash
with my own eyes once, but my wife & kids have described it many
times.  The monitor simply loses the signal from the computer, and the
computer stops responding to all outside contact. I can't ssh into it
anymore.  It is a little confusing because the computer still appears
to be powered up--the lighted power button on the front is still on.
In order to get it to restart, it is necessary to push the button for
a long time as the computer powers down.  After the restart, there's
no trace of trouble. Nothing in /var/log/messages.

What do you think is wrong?  How to find out?

You might suspect bad RAM if the only symptom were the crash. However,
the system stays running forever if you use it via ssh.

-- 
Paul E. Johnson
Professor, Political Science
1541 Lilac Lane, Room 504
University of Kansas